#include <iostream>

using namespace std;

int a[100000];
int b[100000];
int main(){
	int n,m;

	int j = 0;
	while (cin >> n){
		for(int i = 0 ; i < n ; i++){
			int c;
			cin >> c;
			a[i] = c;
		}
		cin >> m;
		bool flag = 0;
		for(int i = 0 ; i < n ; i++){
			if(a[i] == m){
				b[j] = i;
				flag = 1;
				break;
			}
		}
		if(not flag){
			cout << "No" << endl;
		}
		else{
			cout << b[j] << endl;
		}
		j++;
		
	}
	
} 
